This invention relates to a thermocompression bonding apparatus and a thermocompression bonding method for bonding a plurality of members by thermocompression bonding as well as a process of manufacturing a liquid crystal display device.
Various thermocompression bonding apparatus are conventionally known and have such a general construction as shown in FIG. 6.
Referring to FIG. 6, a column or support post 114 is secured to a base 102, and also a guide rail 103b is secured to the base 102.
A pressurization cylinder 109 is secured to an upper portion of the column 114, and a thermocompression head 107 is directly mounted on a rod 109a of the pressurization cylinder 109.
A liquid crystal display (LCD) panel 105 is carried on a platform 104. The platform 104 has a pair of guides 103a received by the guide rail 103b. Thus, the platform 104 can move in the directions indicated by a double-sided arrow mark Y along the guide rail 103b.
A terminal portion 106 of the TAB type has, for example, such a construction as described below. The terminal portion 106 of the TAB type denotes a terminal portion formed by Tape Automated Bonding and is constructed such that copper foil patterns of circuits are adhered to a resin film of polyimide, which serves as a base, and IC chips are adhered to the copper foil patterns of circuits.
Meanwhile, the liquid crystal display panel 105 has fine circuit patterns formed, for example, from an anisotropic conductive film thereon.
In order to bond the terminal portion 106 of the TAB type to the liquid crystal display panel 105 by thermocompression bonding, the pressurization cylinder 109 is rendered operative to move the rod 109a downwardly.
Consequently, the thermocompression head 107 is pressed against the terminal portion 106 of the TAB type so that, for example, output side terminals of electrodes of an IC of the terminal portion 106 of the TAB type and the fine circuit patterns of the liquid crystal display panel 105 formed from an anisotropic conductive film are connected and bonded to each other by thermocompression bonding.
The conventional thermocompression bonding apparatus of the type described above, however, has the following problems.
In particular, the platform 104 for receiving a liquid crystal display panel 105 thereon and the column 114 for the pressurization cylinder 109 are both secured directly to the single base 102.
Accordingly, when the pressurization cylinder 109 operates for thermocompression bonding, the base 102 is deformed by a reaction to the compression force. The influence of the deformation of the base 102 is had on the entire apparatus, and particularly the accuracy in position of the platform 104 for the liquid crystal display panel 105 undergoes a bad influence of the deformation, resulting in degradation in connection accuracy by such thermocompression bonding as described above.
Since the thermocompression head 107 and the rod 109a are directly connected to the column 114, the accuracy in relative position between the liquid crystal display panel 105 and the thermocompression head 107 relies upon the rigidity of the entire apparatus including the base 102.
A possible countermeasure for eliminating an influence of the deformation of the base 102 upon the entire apparatus is to raise the rigidity of the entire thermocompression bonding apparatus to prevent or minimize the deformation of the base. This, however, cannot avoid an increase in scale or in weight of the thermocompression bonding apparatus and cannot meet a demand for miniaturization.
Further, since the base suffers from deformation, it is difficult to further reduce the connection pitch in thermocompression bonding or to raise the connection accuracy.
Further, in order to sufficiently assure the parallelism between the liquid crystal display panel 105 and the thermocompression head 107, it is necessary to increase the part accuracy and the assembly accuracy of each element and prevent thermal deformation of each element.
In order to manufacture a liquid crystal display device using the liquid crystal display panel 105 of a large size and the terminal portion 106 of the TAB type, particularly the pressurization cylinder 109 must generate a high pressure, and it is difficult for the conventional thermocompression bonding apparatus of FIG. 6 to perform fine connection by thermocompression bonding.